This invention relates to a swim fin.
Swim fins substantially increase the surface area of a swimmer""s foot thereby to increase the propulsive force exerted by the foot on the water when swimming. Such fins generally include a fin blade that extends longitudinally beyond a user""s foot for a substantial length. Although useful in water, swim fins are cumbersome and inefficient when worn while walking as the portion of the fin blade that extends beyond the user""s foot severely impedes walking.
Another problem associated with many swim fins is that the fin blade extends longitudinally beyond a foot region of the swim fin, with the result that the fin blade pivots about the foot region when swimming. This causes a reaction force substantially equivalent to the propulsive force exerted by the fin blade on the water, to be exerted on a relatively small area of an upper region of the person""s foot. As a consequence, this exerts a relatively high pressure on the upper region of the person""s foot which can be quite painful.
According to a first aspect of the invention there is provided a swim fin comprising
a foot-pocket formation defining a foot-receiving cavity, the foot-receiving cavity defining a longitudinal axis and having a top side, a bottom side, a toe end, a heel end and two sides that extend between the heel and toe ends; and
a fin blade that is spaced a predetermined distance above the bottom side of the foot-pocket formation and that extends in a direction away from the heel end of the foot-pocket formation, no further than a predetermined distance beyond the length of the foot-pocket formation, thereby to permit walking while wearing the swim fin, in use.
The ratio of the length of the fin blade measured between the toe end of the foot-pocket formation and a front end of the fin blade, with respect to a height of the fin blade measured between the bottom side of the foot-pocket formation and an underside of the fin blade, may be between 1:0.25 and 1:0.4.
Said length of the fin blade may be between 80 mm and 100 mm.
Said height of the fin blade may be between 25 mm and 40 mm.
Optimally, the ratio of said length of the fin blade with respect to said height of the fin blade, may be approximately 1:0.35.
The fin blade may have a substantially planar shape.
The fin blade is integrally formed with the foot-pocket formation.
The fin blade may include a frontal blade portion that extends longitudinally from the toe end of the foot-pocket formation and a pair of side blade portions that each extend transversely with respect to the longitudinal axis of the foot-pocket formation from a different side of the foot-pocket formation between the toe end of the foot-pocket formation and at least a position disposed near the talus of the foot of a person wearing the swim fin, in use.
Each side blade portion may comprise a fixed blade section and a moveable blade section in the form of a flap formation that is hingedly displaceable relative to the fixed blade section about an axis that extends substantially parallel to the longitudinal axis of the foot-pocket formation, between an extended position wherein an upper surface of the flap formation is disposed substantially co-planar with an upper surface of the fixed blade section, thereby increasing the effective surface area of the fin blade during a propulsion stroke of the swim fin, in use, and a collapsed condition wherein the flap formation extends rearwardly with respect to the direction of movement of the fin blade through a body of water.
A swim fin as claimed in claim 9, wherein the fixed blade section of each side blade portion, may includes a stop formation which prevents displacement of the flap formation relative to the fixed blade section beyond said extended position of the flap formation.
According to a second aspect of the invention there is provided a swim fin comprising
a foot-pocket formation defining a foot-receiving cavity, the foot-receiving cavity defining a longitudinal axis and having a top side, a bottom side, a toe end, a heel end and two sides that extend between the heel and toe ends; and
a fin blade that comprises a frontal blade portion that extends longitudinally from the foot-pocket formation in a direction away from the heel end thereof and a pair of side blade portions that each extend transversely with respect to the longitudinal axis of the foot-pocket formation from a different side of the foot-pocket formation between the toe end of the foot-pocket formation and at least a position disposed near the talus of the foot of a person wearing the swim fin, in use.
The frontal blade portion of the fin blade may be spaced a predetermined distance above the bottom side of the foot-pocket formation and extends in a direction away from the heel end of the foot-pocket formation, no further than a predetermined distance beyond the toe end of the foot-pocket formation, thereby to permit walking while wearing the swim fin, in use.
The ratio of the length of the frontal blade portion of the fin blade, may be measured between the toe end of the foot-pocket formation and a front end of the frontal blade portion, with respect to a height of the frontal blade portion of the fin blade, measured between the bottom side of the foot-pocket formation and an underside of the frontal blade portion, is between 1:0.25 and 1:0.4.
Said length of the frontal blade portion of the fin blade, may be between 80 mm and 100 mm.
Said height of the frontal blade portion of the fin blade, may be between 25 mm and 40 mm.
The ratio of said length of the frontal blade portion of the fin blade, with respect to said height of the frontal blade portion, may be approximately 1:0.35.
The fin blade may have a substantially planar shape.
The fin blade may be integrally formed with the foot-pocket formation.
Each side blade portion may comprise a fixed blade section and a moveable blade section in the form of a flap formation that is hingedly displace able relative to the fixed blade section about an axis that extends substantially parallel to the longitudinal axis of the foot-pocket formation, between an extended position wherein an upper surface of the flap formation is disposed substantially co-planar with an upper surface of the fixed blade section, thereby increasing the effective surface area during a propulsion stroke of the swim fin, in use, and a collapsed condition wherein the flap formation extends rearwardly with respect to the direction of movement of the fin blade through a body of water.
The fixed blade section of each side blade portion, may include a stop formation which prevents displacement of the flap formation relative to the fixed blade section beyond said extended position of the flap formation.
According to a third aspect of the invention there is provided a swim fin comprising
a foot-pocket formation defining a foot receiving cavity, the foot receiving cavity defining a longitudinal axis and having a top side, a bottom side, a toe end, a heel end and two sides that extend between the heel and toe ends; and
a fin blade that comprises a frontal blade portion that extends longitudinally from the foot-pocket formation in a direction away from the heel end thereof and a pair of side blade portions that each extend transversely with respect to the longitudinal axis of the foot-pocket formation from a different side of the foot-pocket formation between the toe end of the foot-pocket formation and at least a position disposed near the talus of the foot of a person wearing the swim fin, in use, each side fine blade portion comprising a fixed blade section and a moveable blade section in the form of a flap formation that is hingedly displaceable relative to the fixed blade section about an axis that extends substantially parallel to the longitudinal axis of the foot pocket formation, between an extended position wherein an upper surface of the flap formation is disposed substantially co-planar with an upper surface of the fixed blade section, thereby increasing the effective surface area of the fin blade during a propulsion stroke of the swim fin, in use, and collapsed condition wherein the flap formation extends rearwardly with respect to the direction of movement of the fin blade through a body of water.
The fixed blade section of each side blade portion of the fin blade, may include a stop formation which prevents displacement of the flap formation relative to the fixed blade section beyond said extended position of the flap formation.
The ratio of the length of the frontal blade portion of the fin blade, measured between the toe end of the foot-pocket formation and a front end of the frontal blade portion, with respect to a height of the frontal blade portion measured between the bottom side of the foot-pocket formation and an underside of the frontal blade portion, may be between 1:0.25 and 1:0.4.
Said length of the frontal blade portion may be between 80 mm and 100 mm.
Said height of the frontal blade portion of the fin blade, may be between 25 mm and 40 mm.